The vast twister caused "catastrophic" damage, according to the National Weather Service.
It reported that a "confirmed large and destructive tornado" hit overnight, moving northeast at 40 mph.
Public safety officials in the state posted online: "More dangerous severe weather - tornadoes and flash flooding expected."
The National Weather Service said it had received 22 reports of tornadoes by late Wednesday evening.
One tornado skirted just a few miles north of Joplin, Missouri, on the eighth anniversary of a catastrophic tornado that killed 161 people in the city.
The tornado caused some damage in the town of Carl Junction, about 4 miles north of Joplin airport.
The Arkansas River was approaching historic highs, while the already high Missouri and Mississippi Rivers were again rising after storms that produced dozens of smaller tornadoes.
Forecasters predicted parts of Oklahoma, Missouri and Kansas could see more severe weather today.
